From: scientist77017@gmail.com   
      
   On Tuesday, May 14, 2019 at 6:21:59 AM UTC-5, AK wrote:   
   > On Tuesday, May 14, 2019 at 5:53:47 AM UTC-5, default wrote:   
   > > On Mon, 13 May 2019 19:22:56 -0700 (PDT), AK   
   > >  wrote:   
   > >   
   > > >Electronic can be quite frustrating.   
   > > >   
   > > >I put together a circuit for a laser alarm.   
   > > >   
   > > >It does not work.   
   > > >   
   > > >There is no way to tell if a design will be successful even if you follow   
   the authors exact directions.   
   > > >   
   > > >I will keep plugging away and reading Practical Electronics for Inventors.   
   > > >   
   > > >:-)   
   > >   
   > > If you look at the schematic and have some idea in your mind on how it   
   > > is supposed to work... you take your multi-tester and measure a few   
   > > things like the junction of the resistor and LDR.  If it is greater   
   > > than .6 volts the transistor (assuming you used a bipolar junction   
   > > transistor) should switch on.   
   > >   
   > > Or are you using the 555 schematic?  (The trigger for a 555 has to be   
   > > less than 1/3 the supply voltage)  12V supply the trigger has to dip   
   > > lower than 4V...   
   > >   
   > > Use logic and think about what is supposed to be going on then use the   
   > > meter to see what is really going on.   
   >   
   > How specifically do I measure the junction of the resistor and the LDR?   
   >   
   > I am using the 555 chip.   
   >   
   > Andy   
      
   I asked how to specifically do this, but did not get a reply.   
      
   got a voltmeter to test pin 3&6?   
   when pin 6 is >6v then pin 3 = 0v   
   when pin 6 is <6v then pin 3 = 9v   
      
   Can someone please show me how?   
      
   I assume one probe goes to the pin but where does the other go?   
      
   Thanks.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)